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Full text of "Text Book Of Mechanical Engineering"

Strength of Helical Springs.

425

Gd

C^4

oe referred to radius r (Fig. 378) if w be increased.
Strength    Tm a d*, while stiffness    ~ a d*.

&i.—-The angle of torsion of a round W. I. shaft is to
^ for every 3 feet of length, and the maximum stress is
•- per sq. in. Find the one diameter to satisfy both con-
rxs. Mach. Constr. Exam. 1889.) (See App. K, p. 997.)

22X2       2X8000X36           .          „

-——_.   or ——-, —   -----------^—  ^ d^—^'i&i

O d          7x360    10,500,000, xd       ——

'f ** <3L1 £&m—The angle of torsion being limited to one degree
IO feet of length, find the diameter of shaft to transmit
*t K£O revs. perm. (Hons. Applied Mech. Exam. 1892.)

22X2       2X/XI2O

7x360"   10,500,000 xd

100

^3 =

7x50

and /= 763*8 <f
and/=^2-°

763-8^ =

641,620

and

of  Helical (Spiral) Springs.—In the round
.(Fig-.   379)  the   pull   is  exerted axially,  and   any
f   if*    In   torsion.

16

Extreme elastic stress for steel =89,000 Ibs.

_        . .               89,000             .,

oxid. working stress = — ^ - = 29,600 IDS.

o

«|tiatre-sectioned steel (Fig. 380),

sections,

421.)